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221.
Weiss S Keller M Bernhardt G Buschauer A König B 《Bioorganic & medicinal chemistry》2008,16(22):9858-9866
According to a 'bivalent ligand approach' to increase the affinity of the potent argininamide-type NPY Y(1) receptor antagonist BIBP-3226, dimeric ligands were synthesized in which two molecules of the parent compound were linked by different spacers via N(G)-acylation at the guanidino groups. A synthetic route for the preparation of the title compounds was developed, which includes a copper(I)-catalyzed azide alkyne cycloaddition as the key step. Three bivalent analogues of BIBP-3226 were prepared showing nanomolar antagonistic activity and binding affinity to the NPY Y(1) receptor (calcium assay on HEL cells, radioligand binding assay on SK-N-MC cells), but these ligands were not superior to the parent compound and there was no correlation with the length or the chemical nature of the spacer. A trivalent BIBP-3226 derivate showed, surprisingly, no affinity to the NPY Y(1) receptor at all. 相似文献
222.
Armin Hallmann 《Plant signaling & behavior》2008,3(2):124-127
The sex-inducer of the spherical green alga Volvox carteri is one of the most potent biological effector molecules known: it is released into the medium by sexual males and triggers the switch to the sexual cleavage program in the reproductive cells of vegetatively grown males and females even at concentrations as low as 10-16 M. In an adult Volvox alga, all cells are embedded in an extensive extracellular matrix (ECM), which constitutes >99% of the volume of the spheroid. There exist no cytoplasmic connections between the cells in an adult alga, so any signal transduction between different cells or from the organism''s environment to a reproductive cell must involve the ECM. Recently, a small cysteine-rich extracellular protein, VCRP, was identified in Volvox and shown to be quickly synthesized by somatic cells in response to the sex-inducer. Due to its characteristics, VCRP was speculated to be an extracellular second messenger from somatic cells to reproductive cells. Here a related protein, VCRP2, is presented, exhibiting a 56% amino acid sequence identity with VCRP. Two possible scenarios for signal transduction from the sex-inducer to the reproductive cell are discussed.Key words: cell wall, extracellular matrix, extracellular second messenger, green algae, sex-inducer, sex inducing pheromone, sexual development, stress response, Volvocaceae, wounding 相似文献
223.
Crucifers (Brassicaceae, Cruciferae) are a large family comprisingsome 338 genera and c. 3,700 species. The family includes importantcrops as well as several model species in various fields ofplant research. This paper reports new genome size (GS) datafor more than 100 cruciferous species in addition to previouslypublished C-values (the DNA amount in the unreplicated gameticnuclei) to give a data set comprising 185 Brassicaceae taxa,including all but 1 of the 25 tribes currently recognized. Evolutionof GS was analyzed within a phylogenetic framework based ongene trees built from five data sets (matK, chs, adh, trnLF,and ITS). Despite the 16.2-fold variation across the family,most Brassicaceae species are characterized by very small genomeswith a mean 1C-value of 0.63 pg. The ancestral genome size (ancGS)for Brassicaceae was reconstructed as anc1C = 0.50 pg. Approximately50% of crucifer taxa analyzed showed a decrease in GS comparedwith the ancGS. The remaining species showed an increase inGS although this was generally moderate, with significant increasesin C-value found only in the tribes Anchonieae and Physarieae.Using statistical approaches to analyze GS, evolutionary gainsor losses in GS were seen to have accumulated disproportionatelyfaster within longer branches. However, we also found that GShas not changed substantially through time and most likely evolvespassively (i.e., a tempo that cannot be distinguished betweenneutral evolution and weak forms of selection). The data revealan apparent paradox between the narrow range of small GSs overlong evolutionary time periods despite evidence of dynamic genomicprocesses that have the potential to lead to genome obesity(e.g., transposable element amplification and polyploidy). Toresolve this, it is suggested that mechanisms to suppress amplificationand to eliminate amplified DNA must be active in Brassicaceaealthough their control and mode of operation are still poorlyunderstood. 相似文献
224.
Armin Arabanian Mahdieh Mohammadnejad Saeed Balalaie Jürgen H. Gross 《Bioorganic & medicinal chemistry letters》2009,19(3):887-890
An efficient method for the synthesis of some Gn-RH analogues based on Ugi reaction has been developed. Four-component reaction of N- and C-terminus peptides, aromatic aldehydes and isocyanides affords novel Gn-RH analogues derived from triptorelin and gonadorelin. All of the products were purified using preparative HPLC and the structures were assigned according to MALDI-mass spectrometry data. 相似文献
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228.
Maria Guadalupe Vizoso Pinto Josefina Maria Villegas Jan Peter Rudolf Haase Jürgen Haas Amelie Sophia Lotz Ania Carolina Muntau Armin Baiker 《Proteomics》2009,9(23):5303-5308
The GC content is highly variable among the genomes of different organisms. It has been shown that recombinant gene expression in mammalian cells is much more efficient when GC‐rich coding sequences of a certain protein are used. In order to study protein–protein interactions in Varicella zoster virus, a GC‐low herpesvirus, we have developed a novel luminescence‐based maltose‐binding protein pull‐down interaction screening system (LuMPIS) that is able to overcome the impaired protein expression levels of GC‐low ORFs in mammalian expression systems. 相似文献
229.
Carsten Schleh Christian Mühlfeld Karin Pulskamp Andreas Schmiedl Matthias Nassimi Hans D Lauenstein Armin Braun Norbert Krug Veit J Erpenbeck Jens M Hohlfeld 《Respiratory research》2009,10(1):90
Background
Pulmonary surfactant reduces surface tension and is present at the air-liquid interface in the alveoli where inhaled nanoparticles preferentially deposit. We investigated the effect of titanium dioxide (TiO2) nanosized particles (NSP) and microsized particles (MSP) on biophysical surfactant function after direct particle contact and after surface area cycling in vitro. In addition, TiO2 effects on surfactant ultrastructure were visualized.Methods
A natural porcine surfactant preparation was incubated with increasing concentrations (50-500 μg/ml) of TiO2 NSP or MSP, respectively. Biophysical surfactant function was measured in a pulsating bubble surfactometer before and after surface area cycling. Furthermore, surfactant ultrastructure was evaluated with a transmission electron microscope.Results
TiO2 NSP, but not MSP, induced a surfactant dysfunction. For TiO2 NSP, adsorption surface tension (γads) increased in a dose-dependent manner from 28.2 ± 2.3 mN/m to 33.2 ± 2.3 mN/m (p < 0.01), and surface tension at minimum bubble size (γmin) slightly increased from 4.8 ± 0.5 mN/m up to 8.4 ± 1.3 mN/m (p < 0.01) at high TiO2 NSP concentrations. Presence of NSP during surface area cycling caused large and significant increases in both γads (63.6 ± 0.4 mN/m) and γmin (21.1 ± 0.4 mN/m). Interestingly, TiO2 NSP induced aberrations in the surfactant ultrastructure. Lamellar body like structures were deformed and decreased in size. In addition, unilamellar vesicles were formed. Particle aggregates were found between single lamellae.Conclusion
TiO2 nanosized particles can alter the structure and function of pulmonary surfactant. Particle size and surface area respectively play a critical role for the biophysical surfactant response in the lung. 相似文献230.
Process development in Hansenula polymorpha and Arxula adeninivorans, a re-assessment 总被引:1,自引:0,他引:1
Christoph Stöckmann Marco Scheidle Barbara Dittrich Armin Merckelbach Grit Hehmann Georg Melmer Doris Klee Jochen Büchs Hyun Ah Kang Gerd Gellissen 《Microbial cell factories》2009,8(1):22-10
A range of industrial H. polymorpha-based processes exist, most of them for the production of pharmaceuticals. The established industrial processes lean on the
use of promoters derived from MOX and FMD, genes of the methanol metabolism pathway. In Hansenula polymorpha these promoters are de-repressed upon depletion of a range of carbon sources like glucose and glycerol instead of being induced
by methanol as reported for other methylotrophs. Due to these characteristics screening and fermentation modes have been defined
for strains harbouring such expression control elements that lean on a limited supplementation of glycerol or glucose to a
culture medium. For fermentation of H. polymorpha a synthetic minimal medium (SYN6) has been developed. No industrial processes have been developed so far based on Arxula adeninivorans and only a limited range of strong promoter elements exists, suitable for heterologous gene expression. SYN6 originally designed
for H. polymorpha provided a suitable basis for the initial definition of fermentation conditions for this dimorphic yeast. Characteristics
like osmo- and thermotolerance can be addressed for the definition of culture conditions. 相似文献